RFID (Radio Frequency Identification) labels may be used, among other applications, as a replacement for bar codes. An important advantage of such RFID labels is that they enable remote reading of information from objects that are out of sight. Each label contains an antenna, which may read the radio frequency and may transfer the information and RF tag, which is electronically programmed with unique information to be transmitted. The thickness of the antenna is a major factor for ensuring satisfactory performance. A typical antenna may have a thickness of approximately 3-7 microns to enable acceptable performance. Additionally, the antenna should have a precise shape according to a pre-designed pattern.
RFID labels are categorized as either active or passive. Passive RFID labels operate without a separate external power source and obtain operating power generated from a central reader. Active RFID labels are powered by an internal battery and may be programmable. An important issue for the RFID industry is reducing the price of the labels, especially for passive RFID labels at the item level. Passive RFID labels are consequently much lighter than active tags, less expensive but they have shorter read ranges and require higher-powered readers.
A conventional method of producing antennas for RFID labels is to chemically etch copper or aluminum foils laminated to polyester (PET) films. The thickness of a standard copper film is between 18 microns and 35 microns and accordingly, this process is, very expensive, slow and not environmentally safe. Another technology is to print out the antenna patterns with conductive ink based on pastes containing a high concentration of electrically conductive particles (mainly silver). This process is also expensive. The low electrical conductivity of the inks is another drawback.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.